Air heater



July 14, 1931. N1, N W 1,814,011

AIR HEATER Original Filed Feb. 27, 1925 Mar/9241274 Jnaw- ATTORNEYS i Patented July 14, 1931 UNITED STATES PATENT OFFICE,-

L. SNOW, OF DETROIT, MICHIGAN, ASSIGNOR TO DIAMOND POWER eonr onarrolv, or nn'rnoir, MICHIGAN, A CORPORATION OF mroiriea v AIR HEATER Application'filed February 27, 1925, Serial No. 12,108. Renewed October 9, 1930.

My present invention relates to heat transfer devices, such as, are commonly used for heating air or the like either by means of specially fired furnaces, from hot waste gases or hot gases from any other source, and particularly to a form of such air heat- 61's in which metal materials'may be used to separate the gases between which heat is being transferred.

My invention will be best understood from the following description and the annexed drawings in which Figure 1 represents a vertical sectional elevation of one form of air heater embodying my invention and Figure 2 is a section on the line 22 of Figure 1.

Like reference characters parts in the different views.

In the form of my invention illustrated in Figures 1 and 2, the air is heated by causing the hot gases to first contact wlth the exterior of a set of tubes arranged transversely to the flow of hot gases through which tubes the air to be heated is flowing and then causing the air from this first set of tubes to flow over the exterior of a set of vertical tubes through the interiors of which the hot gases flow. In the form illustrated, I have, arranged the parts so that the heated air from the first set of tubes will be brought in contact first with the'upper ends of the second set of tubes and will flow downward thereafter over the exteriors of this second set of tubes, so that a counter flow between indicate like the heated gases and the airjis obtained and thereby a more satisfactory heat transfer.

In Figures 1 and 2, the vertical fine for the hot gases has a set of tubes 11 located transversely thereover, which tubes may extend horizontally, the tubes being held in any suitablemanner in headers 12, 13 on opposite sides ofthe flue 10. An air inlet duct 14 leads the air to be heated to the left-hand ends of the tubes 11, and a vertical duct 15 at theright-hand end of the tubes 11 leads the air thus heated to the upper part of an air flue casing 16 through which extends a set of vertical tubes 17 with i? their ends in headers 18, 19. The air enters the casing 16 at an inlet 20 and passes out through an outlet 21. Battles 22, 23 and 24.- may be provided to direct the gases back and forth across the exterior of the tubes 17. The casing formed by the various fiues and ducts is preferably divided on a horizontal line just below the header 18 and held by removable fasteners, so that the two parts of the heater may be separated for repair or other purposes. Also the lower part Of. the duct 15 may be provided with a door or doors to give access to the tubes 11 The header '19, in the, form illustrated in Fig ures 1 and 2, is supported on a flexible plate 25 and may be separated therefrom at its outer edges by distance, pieces 26. The ends of the tubes 17 are fastenedv in the header 19 and as such tubes expand, the flexible plate 25 permits this to occur without causing any leakage either, in the header or in the air flue itself.

. It will be noted that the arrangement which I have described is particularly adapt.- ed for the use of metallic walls to separate the two kindsof gases, whereby an effective transfer of heat therebetween will be obtained. At the same time, it is possible'to use in my arrangement relatively expensive metals or alloys thereof for the lower set of tubes ll'which will be subjected to the most intense heat from the hot gases and cheaper metals for the vertical tubes. By arranging the two sets of tubes as I have shown, the lowermost set, which is most liable to injury, can be removed and replaced readily.

It will be understood, that if desired, the hot gases may be caused to flow horizontally instead of vertically; in other words, that the arrangement which I have shown may be operated in other positions than the vertical one which Ih'ave shown.

It will also be understood'that features of my invention may be used either alone or in combination with other features. In this application it will be understood that'where the word air is used it means either ordinary airor any other gas;

WhatI claim as my invention is I. In an air heater, a first set; of. ducts. and a set o f duc'its; extending substantially exit in said air flue at the end adjacent said first set of ducts.

2. In an air heater, a flue for the hot gases, a first set of tubes extending across the flue, headers for the ends of said tubes, a second set of tubes arranged to receive and conduct hot gases from said flue after the gases have passed over the exteriors of the tubes of said first set, headers for the tubes of said second set, an air flue surrounding said second set of tubes, a duct to lead air from said first set of tubes to the portion of the said air flue farthest from the point of entrance of the gases into the tubes of said second set, and an air exit in said air flue.

3. In an air heater, a vertical flue for the hot gases, a first set of tubes extending across the flue, headers for the ends of said tubes on opposite sides of said flue, a second set of tubes above said vertical flue and arranged vertically to receive and conduct hot gases from said Vertical flue after the gases have assed over the exteriors of the tubes of said rst set, headers for said second set of tubes, an air flue surrounding said second set of tubes, a duct to lead air from said first set of tubes to the upper portion of said air flue, and an air exit at the lower part of said air flue.

4. In air heater, a flue for hot gases, a first set of tubes extending across said flue, a second set of tubes extending lengthwise of said flue, whereby one end of said second set of tubes is cooler than the other end, and a duct to lead air from said first set of tubes to a point adjacent the colder ends of said second set of tubes.

5. The method of heating a gas comprising the steps of supplying a flow of heating fluid and passing the gas to be heated first through a plurality of passages transversely across the flow of said heating fluid and thereafter causing the gas to travel counter to the direction of flow of heating fluid.

6. The method of heating a gas comprisingv the steps of supplying a flow of heating fluid and passing the gas to be heated in a divided condition, first transversely across the flow of said heating fluid and thereafter causing the gas to travel counter to the direction of flow of heating fluid.

7. The method of heating a gas comprising the steps of supplying a flow of heating fluid and passing the gas to be heated in a I divided condition, first transversely across the flow of said heating fluid and thereafter uniting the said divisions of gases and causing the same to travel counter to the direction of flow of heating fluid.

8. In an air heater, a flue for the hot gases, a first set of tubes extending across the flue, tube plates for the ends of said tubes, a second set of tubes arranged to receive and conduct hot gases from said flue after the gases have passed over the extee riors of the tubes of said first set, tube plates for the tubes of said second set, an air flue surrounding said second set of tubes, a duct to lead air from said first set of tubes to the portion of said air flue farthest from the point of entrance of the gases into the tubes of said second set, and an air exit in said air flue, the tubes of one of said sets being relatively offset.

9. In an air heater, the combination of an elongated casing, means for flowing a heating fluid longitudinally through said casing and means for flowing a fluid to be heated initially transversely across said casing and subsequently longitudinally through the casing counter to the flow of heating fluid therethrough.

10. In an air heater, the combination of an elongated casing, means for flowing a heating fluid longitudinally through said casing, means for flowing a fluid to be heated transversely across one end of said casing and means for conducting the fluid to be heated from the transverse conducting means to the far end of the casing for discharge into the casing whereby the fluid to be heated may be flowed longitudinally through the casing counter to the flow of heating fluid therethrough.

11. In an air heater, the combination of an elongated casing, means for flowing a heating fluid longitudinally through said casing, tubes for conducting a fluid to be heated initially transversely across said casing, and means for subsequently conducting the fluid to be heated longitudinally through the casing counter to the flow of heating fluid therethrough.

12. In an air heater, the combination of an elongated casing, means for flowing a heating fluid longitudinally through said casing, tubes for conducting a fluid to be heated transversely across one end of said casing, and means for conducting the fluid to be heated from the transverse conducting tubes to the far end of the casing for discharge into the casing whereby the fluid to be heated may be flowed longitudinally through the casing counter to the flow of heating fluid therethrough.

In testimony whereof I aflix my signature.

NORMAN L. SNOW. 

